假如你所在的城市正在创建“国家级卫生城市”，请你以“How to set up a national healthy city?”为题，根据所给提示写一篇80词以上的英语短文

要求：1.不要逐条翻译提示内容，注意逻辑合理；2.语言流畅，书写规范，卷面整洁。

提示用词：throw rubbish; talk loudly; smoke; spit; in public; give seats to the old and children; be polite to others; obey traffic rules; have good life habits; keep ... clean;

    How to set up a national healthy city?